Process for producing processed glyceride fat

ABSTRACT

A process for producing a processed glyceride having a satisfactory color tone and having high purity without the need of a fractionation step, by mitigating the deterioration in a color tone caused by the processing and recycling of a fatty acid ester recovered after an interesterification reaction. The process comprises subjecting a glyceride fat and a fatty acid ester and/or a free fatty acid to interesterification, distilling the reaction product to recover a part or all of fatty acid esters and/or free fatty acids therein, subjecting the distillation fraction recovered to hydrogenation, and to re-distillation or mixing with the fresh fatty acid ester and/or fresh free fatty acid in any order, re-reacting the resultant fraction or mixture with the distillation residue, and separating a fat fraction from the final reaction product, and is characterized in that the content of components other than the fatty acid ester and/or free fatty acid is controlled to 3.0 wt. % or lower.

TECHNICAL FIELD

The present invention relates to a process for producing a processedglyceride fat having an excellent color tone and having high puritywithout the need of a step of fractionating the glyceride fat after aninteresterification reaction.

BACKGROUND ART

So far, interesterification has been one of the effective means as amethod for modifying fats and oils. As this interesterification, thereare a chemical procedure, that is, a metal-catalyzing method of randominteresterification using, as a catalyst, a substance such as an alkalimetal alcoholate, an alkali metal, an alkali metal hydroxide, or thelike, and an enzymatic interesterification method of 1,3-positionspecific or random interesterification using a lipase.

In such interesterification, since fatty acid esters and/or free fattyacids are produced, they are recovered from the reaction product bydistillation after completion of the reaction. Then, they are subjectedto processing such as hydrogenation, and recycled as fatty acid estersand/or free fatty acids for interesterification in some cases (JP3-69516 B). For example, in a process for producing a symmetrictriglyceride such as cacao butter by enzymatic interesterificationbetween a fat rich in oleic acid as a constituent fatty acid, and asaturated fatty acid ester and/or a free fatty acid using a lipase, itis advantageous to hydrogenate fatty acid esters and/or free fatty acidscontaining oleic acid as a main component recovered from the reactionproduct and recycle them as the aforementioned saturated fatty acidester and/or free fatty acid.

In interesterification processes, there is also such a reaction mannerthat an interesterification reaction is performed by a one stage tocontinuous multi-stage manner in order to obtain a reaction product of aprocessed glyceride fat having high purity. That is, in this manner, anunreacted fatty acid ester fraction is selectively left in a reactionsystem after the first stage interesterification reaction, and a freshunreacted fatty acid ester is added thereto, followed by performing theinteresterification reaction of the second stage to obtain a reactionproduct of the processed glyceride fat having high purity, whereby, asubsequent fractionating step becomes unnecessary (WO 96/10643).

DISCLOSURE OF THE INVENTION

However, according to the present inventors' study, in theaforementioned multi-stage interesterification reaction, it has beenfound that, when fatty acid esters and/or free fatty acids recoveredfrom a reaction product are subjected to processing and recycling in theinteresterification reaction at the second or subsequent stage, therearises such a drawback that a color tone of the processed glyceride fatobtained from the final reaction product is deteriorated.

An object of the present invention is to provide a process for producinga processed glyceride fat having a satisfactory color tone and highpurity without causing such drawback and without the need of a step offractionating the glyceride fat.

As a result of the present inventors' intensively study, the presentinvention has been completed. The present invention is a process forproducing a processed glyceride fat, which comprises subjecting aglyceride fat and a fatty acid ester and/or a free fatty acid tointeresterification, distilling the reaction product to recover a partor all of fatty acid esters and/or free fatty acids therein, subjectingthe distillation fraction recovered to re-distillation or mixing withthe fresh fatty acid ester and/or the fresh free fatty acid, and tohydrogenation, in any order, re-reacting the resultant fraction ormixture with the distillation residue, and separating a glyceride fatfraction from the final reaction product.

Preferably, the content of components other than fatty acid estersand/or free fatty acids in the fraction to be mixed with thedistillation residue is reduced to 3.0 wt. % or lower byre-distillation, or mixing with the fresh fatty acid ester and/or thefresh free fatty acid.

BEST MODE FOR CARRYING OUT THE INVENTION

As the raw material glyceride fat to be subjected tointeresterification, edible glyceride fats and oils can be widely used,and examples thereof include vegetable fats and oils such as rapeseedoil, soybean oil, sunflower seed oil, cottonseed oil, peanut oil, ricebran oil, corn oil, safflower oil, olive oil, kapok oil, sesame oil,evening prime-rose oil, palm oil, shea butter, sal fat, cacao butter,coconut oil, palm kernel oil and the like, and animal fats and oils suchas milk fat, beef tallow, lard, fish oil, whale oil and the like. Theycan be used alone or in a combination thereof, and also includeprocessed fats and oils obtained by subjecting them to hydrogenation,fractionation, interesterification, or the like. They can beappropriately selected and used according to a particular object. Forexample, for the purpose of producing hard butter rich in1,3-di-saturated-di-unsaturated triglyceride (hereinafter, referred toas SUS (S: saturated fatty acid, U: unsaturated fatty acid)) components,a fat in which a large amount of unsaturated fatty acids are bound tothe 2-position is preferred is preferable, inter alia, to use a fat richin oleic acid is more preferable.

Further, as the raw material fatty acid ester and/or free fatty acid,various acyl groups can be used and they may also be appropriatelyselected and used according to a particular object. Similarly, for thepurpose of producing hard butter rich in SUS components, the fatty acidis preferably a saturated fatty acid, inter alia, stearic acid is morepreferable. Further, the fatty acid ester is preferably an alcoholester, particularly, a monohydric lower alcohol ester is more preferablefrom a viewpoint of the reactivity and the workability.

In the present invention, the interesterification reaction may be any ofa reaction by an alkali metal-catalyzing method and a reaction by anenzymatic interesterification method. Preferably, in the presentinvention, by performing interesterification in a multi-stage manner, afat having high purity of the objective glyceride fat can be obtainedwithout the need of fractionation. In particular, for the purpose ofproducing hard butter rich in SUS components, it is advantageous toadopt a multi-stage manner in which, as the first stage, a fatty acidester and/or a free fatty acid rich in a saturated fatty acid, and aglyceride fat rich in oleic acid at the 2-position are subjected to theinteresterification reaction, and a part or all of fatty acid estersand/or free fatty acids in the reaction product are distilled off, whenthe reaction is completed. Then, after hydrogenation of the resultantdistillation fraction, the hydrogenated fraction and the residue of theabove distillation are subjected to the interesterification reactionagain to obtain the processed glyceride fat having higher purity thanthat of the fat obtained in the first stage reaction and, if necessary,repeating the reaction again.

The distillation temperature after completion of the reaction at a stageprior to the final stage, i.e., after completion of the reaction of thefirst stage, the second stage, or the like is as low as possible such asat 200° C. or lower under reduced pressure conditions, more specificallyand preferably, at about 170° C. to 180° C. under reduced pressureconditions of 1 to 3 Torr. Further, the distillation for separating theprocessed glyceride after completion of the reaction at the final stageis preferably performed by, firstly, distillation at about 170° C. to180° C. under reduced pressure conditions of 1 to 3 Torr, and then,steam distillation at about 230° C. to 240° C. under reduced pressureconditions of 1 to 3 Torr.

In the distillation step at a temperature as low as possible such as at200° C. or lower under reduced pressure conditions, it is preferablethat the recovery of fatty acid esters and/or free fatty acids from thereaction product is usually 50% or more of the fatty acid esters and/orfree fatty acids present in the reaction system because, when the amountof remaining unsaturated fatty acid esters coming out by the reaction ofthe first stage, second stage, or the like becomes larger, the desiredpurity of the objective processed glyceride fat is hardly obtainable.Further, in the steam distillation step at about 230° C. to 240° C.under reduced pressure conditions, it is preferable to recover almostall of the fatty acid esters and/or free fatty acids.

However, when the interesterification reaction is performed in amulti-stage manner, it is required to perform reaction steps the samenumber of times as that corresponding to the number of stages as well asthe distillation stapes and the steam distillation step. Then, thereactants readily undergo thermal history in respective steps and manyby-products are formed in the distillation steps to steam distillationstep during the reaction.

When these by-products as well as a distillation fraction of fatty acidesters and/or free fatty acids formed, in particular, a distillationfraction recovered by the steam distillation at 230° C. or higher arehydrogenated and used in the interesterification reaction at a nextstage or another interesterification reaction, a deterioratingphenomenon in a color tone of the processed glyceride fat after thefinal stage reaction may be caused. However, in the present invention,the above deteriorating phenomenon in a color tone can be solved byreducing the content of components other than fatty acid esters and/orfree fatty acids in a distillation fraction containing fatty acid estersand/or free fatty acids recovered from the reaction product byre-distillation or mixing with the fresh fatty acid ester and/or thefresh free fatty acid, preferably by controlling the content to 3.0 wt.% or lower.

As aspects of reducing the content of components other than fatty acidesters and/or free fatty acids, there are methods:

(1) wherein fatty acid esters and/or fatty acids distilled from thereaction product by steam distillation at about 230° C. or higher at thefinal stage is mixed and combined with the fatty acid ester and/or-freefatty acid scarcely containing impurities such as a commerciallyavailable reagent, or the like, or with the fresh fatty acid esterand/or fresh free fatty acid which has never undergone a reaction stepand does not contain an increased amount of impurities such asunsaponifiable matter so that the content of components other than fattyacid esters and/or free fatty acids is 3.0 wt. % or lower;

(2) wherein fatty acid esters and/or free fatty acids distilled from areaction product by distillation at about 200° C. or lower at any stageup to that prior to the final stage are used in an large amount, fattyacid esters and/or free fatty acids distilled from a reaction product bysteam distillation at about 230° C. at the final stage are used in asmall amount, and they are mixed and combined so that the content ofcomponents other than fatty acid esters and/or free fatty acids is 3.0wt. % or lower; or

(3) wherein only fatty acid esters and/or free fatty acids distilledfrom the reaction product by steam distillation at about 230° C. orhigher at the final stage, or a mixture obtained by mixing and combiningfatty acid esters and/or free fatty acids distilled from a reactionproduct by distillation at about 200° C. or lower at any stage up tothat prior to the final stage with fatty acid esters and/or free fattyacids distilled from the reaction product by steam distillation at about230° C. or higher at the final stage at an arbitrary ratio are(is)subjected to re-distillation treatment at about 200° C. to 210° C. underreduced pressures of 1 to 3 Torr, so that the content of componentsother than fatty acid esters and/or free fatty acids in the fatty acidesters and/or the free fatty acids is 3.0 wt. % or lower; and the like.

These steps for reducing components other than fatty acid esters and/orfree fatty acids can be performed in combination with hydrogenation inany order, followed by subjecting to the re-reaction with a distillationresidue at any stage up to that prior to the final stage. Thehydrogenation step of fatty acid esters and/or fatty acids for recyclingis preferably maximum hydrogenation in order to obtain the processedglyceride fat having high purity. In addition, regarding the fatty acidester and/or free fatty acid containing no impurities such as acommercially available reagent, or the like, or the fresh fatty acidester and/or the fresh free fatty acid which has never undergone areaction step, maximum hydrogenation is also preferable.

In conversion of triglycerides by an enzymatic interesterificationreaction of fats and oils, a fatty acid ester and/or a free fatty acidare used together, and, in this reaction system, triglycerides (TG),diglycerides (DG), water (H₂O) and free fatty acids (FA) are present inan equilibrium state as follows:TG+H₂O=DG+FA

Here, the larger the amount of FA present is, the more the hydrolysisreaction toward the right direction for formation of FA is suppressed.Therefore, when a free fatty acid is added to an interesterificationreaction system between a fat and a fatty acid ester, the hydrolysisreaction is suppressed, and the production of diglycerides,consequently, the production of SSA can be suppressed upon production ofhard butter rich in SUS components without reduction of a reaction rateand without the need of a solvent.

In the present invention, the higher an acid value indicating an amountof a free fatty acid fraction present in fatty acid esters and/or thefree fatty acids to be recycled is, the more the advantages of thepresent invention are enhanced. However, when the acid value exceeds 30,a rate of the interesterification reaction which is the main reaction isreduced and a conversion rate of the objective triglyceride isremarkably decreased. In addition, crystals of free fatty acids are aptto be precipitated. For preventing this, it is required to raise areaction temperature to around 60° C. However, a reaction under such ahigh temperature generally accelerates inactivation of an enzyme, and isundesired. Therefore, preferably, the acid value of fatty acid estersand/or free fatty acids is 30 or less, in particular, 20 or less. Inaddition, when the acid value is less than 8, the effect of suppressinghydrolysis is scarcely observed. Therefore, preferably, the acid valueof fatty acid esters and/or free fatty acids is 8 or more and, inparticular, when the interesterification reaction is performed at amulti-stage, the acid value is preferably 10 or more.

The content of components other than fatty acid esters and/or free fattyacids in the fatty acid ester and/or free fatty acid fractioncorresponds to the content (%) of unsaponifiable matter. The amountsother than the amount of fatty acid esters and/or free fatty acidsreferred to in Examples hereinafter are those measured in terms of thecontent of unsaponifiable matter. More specifically, according toA.O.C.S. Official Method Ca 6a-40 Unsaponifiable Matter, the proceduresup to Procedure 7 are performed to obtain unsaponifiable matter, this isdiluted 10-fold with carbon tetrachloride, 0.5 to 0.7 μl of the dilutionis injected into gas chromatography (gas chromatography proceduralconditions are shown hereinafter), the content of fatty acid contaminantin the unsaponifiable matter is calculated from the resultingquantitative analysis value, and the content of unsaponifiable mattercan be calculated by the following equation.Content of unsaponifiable matter (%)=weight of unsaponifiable matter(g)×(100−content of fatty acids contaminant in unsaponifiable matters(%))÷weight of sample used (g).

Gas chromatography procedural conditions (Shimadzu GC-7A)

-   Injection Temp: 350° C.-   Column Temp: 150° C.→350° C. (4° C./min)-   10 min hold-   Column: 0.5 m×2.3 mm-   Liquid phase: Silicon OV-17 1.5%-   Support: Shimalite W (AW-DMCS)-   Director: FID-   Carrier gas: N2

The distillation residue in the present invention is a residue obtainedby, after the enzymatic interesterification reaction between the rawmaterial glyceride fat and the raw material fatty acid ester and/or freefatty acid, distilling a reaction product to remove and recover a partor all of fatty acid esters and/or free fatty acids therefrom. Thus, SUScomponents of the objective processed glyceride fat are concentratedtherein. The amount of SUS components of the processed glyceride fat inthe distillation residue after aforementioned one stageinteresterification reaction between a stearic acid ester and aglyceride fat rich in oleic acid is 40 to 50 wt. %.

The re-reaction at the second or subsequent stage can be performed bymixing and combining the distilled residue and the fatty acid estersand/or free fatty acids at, usually, the same ratio as that of thereaction substrate of the first stage. However, the mixing and combiningratio of the distilled residue and fatty acid esters and/or free fattyacids may be changed depending on purity of the objective finalprocessed glyceride fat.

For separating the glyceride fat fraction from the final reactionproduct, it is preferable that, after the final stageinteresterification reaction, fatty acid esters and/or free fatty acidsare distilled off by distillation at about 170° C. to 180° C. underreduced pressure conditions of 1 to 3 Torr, followed by steamdistillation purification at about 230° C. to 240° C. under reducedpressure conditions of 1 to 3 Torr to remove monoglycerides (MG),diglycerides (DG) and unsaponifiable matter which produced by theinteresterification reaction, as well as fatty acid esters and/or freefatty acids remained without being distilled off at about 170° C. to180° C. under reduced pressure conditions of 1 to 3 Torr.

The processed glyceride fat is typically hard butter rich in SUScomponents and, at this time, the preferred content of SUS components is50 wt. % or more, desirably 60 wt. % or more. Therefore, a fractionationstep is not required. According to the present invention, hard butter ofgood quality which has the contents of DG components and SSS componentsof 5.0 wt. % or less, and 4.0 wt. % or less, desirably 3.0 wt. % or lessand 2.5 wt. % or less, respectively, can be obtained.

EXAMPLES

Hereinafter, embodiments of the present invention will be illustrated byExamples, but these Examples are merely exemplification, and the spiritof the present invention is not limited by these Examples. In Examples,both of parts and percents are by weight.

Example 1

(1) Preparation of Re-distilled Ethyl Stearate

A mixed oil obtained by mixing 80 parts of commercially available ethylstearate and 20 parts of a high oleic sunflower deacidified oil washeated at 110° C. under reduced pressure to dehydrate the mixture untilthe moisture content became 70 ppm. The dehydrated reaction substratewas passed through a column packed with 120 g of diatomaceous earthcarrying a lipase (originated from Rhizopus nibeus) having1,3-specificity at 40° C. and at a flow rate of 50 g/hr to perform aninteresterification reaction. A reaction product was finally recoveredfrom the reaction oil at 230° C. for 90 minutes under reduced pressureconditions of 2 Torr, from which fatty acid esters and/or free fattyacids were obtained and subjected to maximum hydrogenation. The contentof components other than fatty acid esters and/or free fatty acids was4.1 wt. %. A portion of this was distilled at 210° C. under reducedpressure conditions of 2 Torr to prepare re-distilled ethyl stearatefrom which fatty acid ester and/or free fatty acid components other thanfatty acid esters and/or free fatty acids were removed. The content ofcomponents other than fatty acid esters and/or free fatty acids in there-distilled fatty acid esters and/or free fatty acids was 1.9 wt. %.The acid value of fatty acid esters and/or free fatty acids was adjustedto 15.

(2) Preparation of Interesterification Reaction Fat

A mixed oil obtained by mixing 80 parts of the re-distilled fatty acidesters and/or free fatty acids prepared in (1) and 20 parts of adeacidified high oleic sunflower oil was heated at 110° C. under reducedpressure to dehydrate the mixture until the moisture content became 70ppm. Then, the above reaction substrate was passed through a columnpacked with 120 g of diatomaceous earth carrying lipase (originated fromRhizopus nibeus) having the 1,3-specificity and interesterificationactivating at 40° C. and at a flow rate of 50 g/hr to perform aninteresterification reaction. The resulting interesterification reactionoil was subjected to purification distillation at 170° C. to 180° C.under reduced pressure conditions of 2 Torr to distill off a portion offatty acid esters (71.3 wt. %) mainly combining oleic acid from thereaction product to obtain a distillation residue in which theinteresterification reaction fat was concentrated. Then, thisconcentrated interesterification reaction fat was mixed with there-distilled fatty acid esters and/or free fatty acids prepared in (1),and the mixture was adjusted so that glyceride fat:fatty acid estersand/or free fatty acid became 20 parts:80 parts. Similarly, dehydrationtreatment was performed, and the interesterification reaction throughthe column was performed again and, thereafter, the resultinginteresterification reaction oil was treated at 170° C. to 180° C. underreduced pressure conditions of 2 Torr to distill off fatty acid esterscombining oleic acid from the reaction product. Then, steam distillationpurification was performed at about 230° C. to 240° C. under reducedpressure conditions of 2 Torr to obtain the final proceeded glyceridefat. The content of components other than fatty acid esters and/or freefatty acids in the fatty acid esters and/or free fatty aids which hadbeen recycled in the reaction was 1.9 wt. %. Thus obtainedinteresterification reaction fat was decolored and deodorized accordingto a conventional method, and the color tone thereof was measured byLovibond method (prescribed by Japan Oil Chemistry Society Standard FatAnalysis Test Method 2.2.1.1.-1996). As a result, R was 0.8 and Y was4.8. The quality of the final processed glyceride fat was SUScomponents: 81.5 wt. %, DG components: 2.7 wt. %, SSS components: 2.3wt. %.

Example 2

A part of the fatty acid esters and/or free fatty acids (the content ofcomponents other than fatty acid esters and/or free fatty acids in thefatty acid esters and/or free fatty acids was 4.1 wt. %) from thereaction product obtained in Example 1 was distilled at 210° C. underreduced pressure conditions of 2 Torr to obtain the re-distilled fattyacid esters and/or free fatty acids (the content of components otherthan fatty acid esters and/or free fatty acids in the re-distilled fattyacid esters and/or free fatty acids was 2.8 wt. %), and the acid valuethereof was adjusted to 15 to obtain the final processed glyceride fatunder the same conditions as those of Example 1. As a result, a colortone was R: 1.3, Y: 7.1. The quality of the final processed glyceridefat was SUS components: 81.3 wt. %, DG components: 2.8 wt. %, SSScomponents: 2.4 wt. %.

Similarly, the content of components other than fatty acid esters and/orfree fatty acids in the fatty acid esters and/or free fatty acids wascontrolled to 3.3 wt. %, and the acid value was adjusted to 15 to obtainthe final processed glyceride under the same conditions as those ofExamplel. The fat had R: 6.1, Y: 58.0. Thus, it has been found that acolor tone is significantly improved by controlling the content ofcomponents other than fatty acid esters and/or free fatty acids in thefatty acid esters and/or free fatty acids to 3.0 wt. % or lower. At thistime, the quality of the final processed glyceride fat was SUScomponents: 80.8 wt. %, DG components: 2.8 wt. %, SSS components: 2.3wt. %.

Commercially available stearic acid ester (trade name “Ethyl Stearate(guaranteed)” manufactured by Inoue Koryo Seizosho Co., Ltd.) andstearic acid (trade name “Stearic Acid (guaranteed)” manufactured byWako Pure Chemical Industries, Ltd.) were mixed and combined, the acidvalue was adjusted to 15 (components other than fatty acid esters and/orfree fatty acids were not detected), the same distilled residue as thatobtained in Example 1 was used and the final processed glyceride fat wasobtained under the same conditions as those of Example 1. As a result, acolor tone was R: 0.4, Y:4.1. The quality of the final processedglyceride fat was SUS components: 81.7 wt. %, DG: components 2.5 wt. %,SSS components: 2.2 wt. %.

Comparative Example 1

According to the same manner as that of Example 1, the processedglyceride fat was obtained except that fatty acid esters and/or freefatty acids from the reaction product in (1) were used withoutre-distillation. As a result, a color tone was R: 11.0, Y: 79.9. Thequality of the final processed glyceride fat was SUS components: 80.2wt. %, DG components: 2.9 wt. %, SSS components: 2.4 wt. %.

In view of the above results, in Examples 1 and 2 in which there-distilled fatty acid esters and/or free fatty acids recovered fromthe reaction product by distillation were used as the fatty acid estersand/or free fatty acids to be recycled, a color tone of theinteresterification reaction fat is significantly improved as comparedwith that of Comparative Example 1 in which re-distillation is notperformed. Thus, even when re-distillation is performed, an significantadvantage can be obtained by controlling the content of components otherthan fatty acid esters and/or free fatty acids in the fatty acid estersand/or free fatty acids to 3.0 wt. % or lower.

INDUSTRIAL APPLICABILITY

As described above, in a process for producing a processed glyceride fatwhich comprises subjecting a glyceride fat and a fatty acid ester and/ora free fatty acid to interesterification, distilling the reactionproduct to recover a part or all of fatty acid esters and/or free fattyacids therein, subjecting the distillation fraction recovered tohydrogenation, and to re-distillation or mixing with the fresh fattyacid ester and/or the fresh free fatty acid in any order, re-reactingthe resultant fraction or mixture with the distillation residue, andseparating the glyceride fat fraction from the final reaction product,such an excellent advantage that the processed glyceride fat having highpurity and a significantly improved color tone is obtained, can beexerted without the need of fractionation by reducing the content ofcomponents other than fatty acid esters and/or free fatty acids in thefatty acid esters and/or free fatty acids to control the content,preferably, at 3.0 wt. % or lower.

1. A process for producing a processed glyceride fat, which comprisessubjecting a glyceride fat and a fatty acid ester and/or a free fattyacid to interesterification, distilling the reaction product to recovera part or all of fatty acid esters and/or free fatty acids therein,subjecting the distillation fraction recovered to re-distillation ormixing with the fresh fatty acid ester and/or the fresh free fatty acid,and to hydrogenation, in any order, re-reacting the resultant fractionor mixture with the distillation residue, and separating the glyceridefat fraction from the final reaction product.
 2. The process forproducing a processed glyceride fat according to claim 1, wherein thecontent of components other than fatty acid esters and/or free fattyacids in a fraction to be mixed with the distillation residue is reducedto 3.0 wt. % or lower by re-distillation or mixing with the fresh fattyacid ester and/or the fresh free fatty acid.
 3. The process forproducing a processed glyceride fat according to claim 1, wherein theprocessed glyceride fat is hard butter, the 2-position of a raw materialglyceride fat is rich in an unsaturated constituent fatty acid, a rawmaterial fatty acid ester and/or free fatty acid are rich in a saturatedfatty acid ester or a saturated fatty acid, and interesterification is a1,3-position specific reaction.